Non-petroleum-based, liquid transportation fuels may provide economic, security and environmental benefits. An example of non-petroleum based source is biomass. Liquid fuels derived from biomass are entering the market, driven by factors such as, but not limited to, oil price spikes and need for increased energy security. Further, due to government legislation requiring higher Renewable Fuels Standards (RFS), there is an increasing need for liquid fuels derived from biomass that may be fungible at high concentrations with current transportation fuels.
The examples of liquid fuels derived from biomass may include, but are not limited to, ethanol and biodiesel.
Ethanol may be directly used in blends with gasoline up to 10 v/v % blends in the United States. However, Ethanol content higher than 15% in the blends with gasoline may cause unacceptable corrosion in both blending equipment and consumer cars that are not especially equipped to deal with ethanol.
Biodiesel is also a widespread fuel which may be used as a diesel substitute. Some states in the United States already require biodiesel/diesel blends of up to 2% biodiesel. “Bio-Diesel” is one such product that may be produced by subjecting a base vegetable oil to a transesterification process using methanol to convert the base oil to desired methyl esters. After processing, the products have very similar combustion properties as compared to petroleum-derived hydrocarbons. However, Biodiesel may present engine plugging problems when used at very low temperatures, in winter, due to unfavorable cold flow properties. Biodiesel may also present storage and stability problems; e.g., fatty esters can undergo hydrolysis reactions increasing the acidity of the fuel and, hence, its corrosiveness. Further, biodiesel may also present poor oxidative stability, propensity to gel in cold climates, and higher cost. Further, bacterial growth may take place on biodiesel during long storage periods.
Unmodified vegetable oils and fats have also been used as additives in diesel fuel to lower cost and improve the lubricity of the fuel. However, problems such as injector coking and the degradation of combustion chamber conditions have been associated with these unmodified additives.
Processes for converting vegetable oil into hydrocarbons have been developed. However, these processes have often involved harsh reaction conditions, or the products from the reaction exhibit undesirable properties (such as high pour and cloud points) which render them unsuitable for use in diesel fuel. Further, these processes require significant quantities of hydrogen which increases the overall cost of producing the fuel.
As such, development of a new process of converting biomass to renewable hydrocarbon that would overcome the issue of corrosion, storage and stability could be a significant contribution to the art and to the economy.